drivers/iio/adc/ti-adc084s021.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /**
   3  * Copyright (C) 2017 Axis Communications AB
   4  *
   5  * Driver for Texas Instruments' ADC084S021 ADC chip.
   6  * Datasheets can be found here:
   7  * http://www.ti.com/lit/ds/symlink/adc084s021.pdf
   8  */
   9
  10 #include <linux/err.h>
  11 #include <linux/spi/spi.h>
  12 #include <linux/module.h>
  13 #include <linux/interrupt.h>
  14 #include <linux/iio/iio.h>
  15 #include <linux/iio/buffer.h>
  16 #include <linux/iio/triggered_buffer.h>
  17 #include <linux/iio/trigger_consumer.h>
  18 #include <linux/regulator/consumer.h>
  19
  20 #define ADC084S021_DRIVER_NAME "adc084s021"
  21
  22 struct adc084s021 {
  23         struct spi_device *spi;
  24         struct spi_message message;
  25         struct spi_transfer spi_trans;
  26         struct regulator *reg;
  27         struct mutex lock;
  28         /*
  29          * DMA (thus cache coherency maintenance) requires the
  30          * transfer buffers to live in their own cache line.
  31          */
  32         u16 tx_buf[4] ____cacheline_aligned;
  33         __be16 rx_buf[5]; /* First 16-bits are trash */
  34 };
  35
  36 #define ADC084S021_VOLTAGE_CHANNEL(num)                  \
  37         {                                                      \
  38                 .type = IIO_VOLTAGE,                                 \
  39                 .channel = (num),                                    \
  40                 .indexed = 1,                                        \
  41                 .scan_index = (num),                                 \
  42                 .scan_type = {                                       \
  43                         .sign = 'u',                                       \
  44                         .realbits = 8,                                     \
  45                         .storagebits = 16,                                 \
  46                         .shift = 4,                                        \
  47                         .endianness = IIO_BE,                              \
  48                 },                                                   \
  49                 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),        \
  50                 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),\
  51         }
  52
  53 static const struct iio_chan_spec adc084s021_channels[] = {
  54         ADC084S021_VOLTAGE_CHANNEL(0),
  55         ADC084S021_VOLTAGE_CHANNEL(1),
  56         ADC084S021_VOLTAGE_CHANNEL(2),
  57         ADC084S021_VOLTAGE_CHANNEL(3),
  58         IIO_CHAN_SOFT_TIMESTAMP(4),
  59 };
  60
  61 /**
  62  * Read an ADC channel and return its value.
  63  *
  64  * @adc: The ADC SPI data.
  65  * @data: Buffer for converted data.
  66  */
  67 static int adc084s021_adc_conversion(struct adc084s021 *adc, void *data)
  68 {
  69         int n_words = (adc->spi_trans.len >> 1) - 1; /* Discard first word */
  70         int ret, i = 0;
  71         u16 *p = data;
  72
  73         /* Do the transfer */
  74         ret = spi_sync(adc->spi, &adc->message);
  75         if (ret < 0)
  76                 return ret;
  77
  78         for (; i < n_words; i++)
  79                 *(p + i) = adc->rx_buf[i + 1];
  80
  81         return ret;
  82 }
  83
  84 static int adc084s021_read_raw(struct iio_dev *indio_dev,
  85                            struct iio_chan_spec const *channel, int *val,
  86                            int *val2, long mask)
  87 {
  88         struct adc084s021 *adc = iio_priv(indio_dev);
  89         int ret;
  90
  91         switch (mask) {
  92         case IIO_CHAN_INFO_RAW:
  93                 ret = iio_device_claim_direct_mode(indio_dev);
  94                 if (ret < 0)
  95                         return ret;
  96
  97                 ret = regulator_enable(adc->reg);
  98                 if (ret) {
  99                         iio_device_release_direct_mode(indio_dev);
 100                         return ret;
 101                 }
 102
 103                 adc->tx_buf[0] = channel->channel << 3;
 104                 ret = adc084s021_adc_conversion(adc, val);
 105                 iio_device_release_direct_mode(indio_dev);
 106                 regulator_disable(adc->reg);
 107                 if (ret < 0)
 108                         return ret;
 109
 110                 *val = be16_to_cpu(*val);
 111                 *val = (*val >> channel->scan_type.shift) & 0xff;
 112
 113                 return IIO_VAL_INT;
 114         case IIO_CHAN_INFO_SCALE:
 115                 ret = regulator_enable(adc->reg);
 116                 if (ret)
 117                         return ret;
 118
 119                 ret = regulator_get_voltage(adc->reg);
 120                 regulator_disable(adc->reg);
 121                 if (ret < 0)
 122                         return ret;
 123
 124                 *val = ret / 1000;
 125
 126                 return IIO_VAL_INT;
 127         default:
 128                 return -EINVAL;
 129         }
 130 }
 131
 132 /**
 133  * Read enabled ADC channels and push data to the buffer.
 134  *
 135  * @irq: The interrupt number (not used).
 136  * @pollfunc: Pointer to the poll func.
 137  */
 138 static irqreturn_t adc084s021_buffer_trigger_handler(int irq, void *pollfunc)
 139 {
 140         struct iio_poll_func *pf = pollfunc;
 141         struct iio_dev *indio_dev = pf->indio_dev;
 142         struct adc084s021 *adc = iio_priv(indio_dev);
 143         __be16 data[8] = {0}; /* 4 * 16-bit words of data + 8 bytes timestamp */
 144
 145         mutex_lock(&adc->lock);
 146
 147         if (adc084s021_adc_conversion(adc, &data) < 0)
 148                 dev_err(&adc->spi->dev, "Failed to read data\n");
 149
 150         iio_push_to_buffers_with_timestamp(indio_dev, data,
 151                                            iio_get_time_ns(indio_dev));
 152         mutex_unlock(&adc->lock);
 153         iio_trigger_notify_done(indio_dev->trig);
 154
 155         return IRQ_HANDLED;
 156 }
 157
 158 static int adc084s021_buffer_preenable(struct iio_dev *indio_dev)
 159 {
 160         struct adc084s021 *adc = iio_priv(indio_dev);
 161         int scan_index;
 162         int i = 0;
 163
 164         for_each_set_bit(scan_index, indio_dev->active_scan_mask,
 165                          indio_dev->masklength) {
 166                 const struct iio_chan_spec *channel =
 167                         &indio_dev->channels[scan_index];
 168                 adc->tx_buf[i++] = channel->channel << 3;
 169         }
 170         adc->spi_trans.len = 2 + (i * sizeof(__be16)); /* Trash + channels */
 171
 172         return regulator_enable(adc->reg);
 173 }
 174
 175 static int adc084s021_buffer_postdisable(struct iio_dev *indio_dev)
 176 {
 177         struct adc084s021 *adc = iio_priv(indio_dev);
 178
 179         adc->spi_trans.len = 4; /* Trash + single channel */
 180
 181         return regulator_disable(adc->reg);
 182 }
 183
 184 static const struct iio_info adc084s021_info = {
 185         .read_raw = adc084s021_read_raw,
 186 };
 187
 188 static const struct iio_buffer_setup_ops adc084s021_buffer_setup_ops = {
 189         .preenable = adc084s021_buffer_preenable,
 190         .postenable = iio_triggered_buffer_postenable,
 191         .predisable = iio_triggered_buffer_predisable,
 192         .postdisable = adc084s021_buffer_postdisable,
 193 };
 194
 195 static int adc084s021_probe(struct spi_device *spi)
 196 {
 197         struct iio_dev *indio_dev;
 198         struct adc084s021 *adc;
 199         int ret;
 200
 201         indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*adc));
 202         if (!indio_dev) {
 203                 dev_err(&spi->dev, "Failed to allocate IIO device\n");
 204                 return -ENOMEM;
 205         }
 206
 207         adc = iio_priv(indio_dev);
 208         adc->spi = spi;
 209
 210         /* Connect the SPI device and the iio dev */
 211         spi_set_drvdata(spi, indio_dev);
 212
 213         /* Initiate the Industrial I/O device */
 214         indio_dev->dev.parent = &spi->dev;
 215         indio_dev->dev.of_node = spi->dev.of_node;
 216         indio_dev->name = spi_get_device_id(spi)->name;
 217         indio_dev->modes = INDIO_DIRECT_MODE;
 218         indio_dev->info = &adc084s021_info;
 219         indio_dev->channels = adc084s021_channels;
 220         indio_dev->num_channels = ARRAY_SIZE(adc084s021_channels);
 221
 222         /* Create SPI transfer for channel reads */
 223         adc->spi_trans.tx_buf = adc->tx_buf;
 224         adc->spi_trans.rx_buf = adc->rx_buf;
 225         adc->spi_trans.len = 4; /* Trash + single channel */
 226         spi_message_init_with_transfers(&adc->message, &adc->spi_trans, 1);
 227
 228         adc->reg = devm_regulator_get(&spi->dev, "vref");
 229         if (IS_ERR(adc->reg))
 230                 return PTR_ERR(adc->reg);
 231
 232         mutex_init(&adc->lock);
 233
 234         /* Setup triggered buffer with pollfunction */
 235         ret = devm_iio_triggered_buffer_setup(&spi->dev, indio_dev, NULL,
 236                                             adc084s021_buffer_trigger_handler,
 237                                             &adc084s021_buffer_setup_ops);
 238         if (ret) {
 239                 dev_err(&spi->dev, "Failed to setup triggered buffer\n");
 240                 return ret;
 241         }
 242
 243         return devm_iio_device_register(&spi->dev, indio_dev);
 244 }
 245
 246 static const struct of_device_id adc084s021_of_match[] = {
 247         { .compatible = "ti,adc084s021", },
 248         {},
 249 };
 250 MODULE_DEVICE_TABLE(of, adc084s021_of_match);
 251
 252 static const struct spi_device_id adc084s021_id[] = {
 253         { ADC084S021_DRIVER_NAME, 0},
 254         {}
 255 };
 256 MODULE_DEVICE_TABLE(spi, adc084s021_id);
 257
 258 static struct spi_driver adc084s021_driver = {
 259         .driver = {
 260                 .name = ADC084S021_DRIVER_NAME,
 261                 .of_match_table = of_match_ptr(adc084s021_of_match),
 262         },
 263         .probe = adc084s021_probe,
 264         .id_table = adc084s021_id,
 265 };
 266 module_spi_driver(adc084s021_driver);
 267
 268 MODULE_AUTHOR("Mårten Lindahl <martenli@axis.com>");
 269 MODULE_DESCRIPTION("Texas Instruments ADC084S021");
 270 MODULE_LICENSE("GPL v2");
 271 MODULE_VERSION("1.0");